Suspension microstructure and a fabrication method for the same

Abstract

A suspension microstructure and its fabrication method, in which the method comprises the steps of: forming at least one insulation layer with inner micro-electro-mechanical structures on an upper surface of a silicon substrate, the micro-electro-mechanical structure includes at least one microstructure and a plurality of metal circuits that are independent from each other, the micro-electro-mechanical structures have an exposed portion on the surface of the insulation layer, and the exposed portion is provided with through holes or stacked metal-via layers correspondingly to the predetermined etching spaces of the micro-electro-mechanical structures, the above predetermined etching spaces and the stacked metal-via layers only penetrate the insulation layer; forming a photoresist with an opening on the upper surface of the exposed portion, and the opening of the photoresist is located outside all the through holes or the stacked metal-via layers; subsequently, conducting etching to realize the suspension of the microstructures.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method for fabricating a micro-electro-mechanical structure, and more particularly to a suspension microstructure and its fabrication method, which can effectively avoid improper erosion, and further simplify the mask and reduce the package cost.[0003]2. Description of the Prior Art[0004]The existing semiconductor micro-electro-mechanical systems comprises various semiconductor microstructures, such as the unmovable probe, channel, chamber structure, or the movable spring, linkage rod, gear (rigid body movement or flexible deformation), etc.[0005]Integrating the above different structures with the related semiconductor circuit can form various semiconductor applications. Thus, how to utilize the fabricating method to improve the various functions of the microstructure is the key index of the semiconductor electromechanical system in the future and is also a rigorous challenge of furthe...

AI Technical Summary

Benefits of technology

[0019]The primary objective of the present invention is to provide a suspension microstructure and its fabrication method, which can effectively avoid improper erosion and exposure.

Problems solved by technology

Thus, how to utilize the fabricating method to improve the various functions of the microstructure is the key index of the semiconductor electromechanical system in the future and is also a rigorous challenge of further developing the chip in the future.

The transverse etching will cause the undercut problems.

However, the selectivity of the dry etching is lower than that of the wet etching (the etching process of the dry etching is generally a physical interaction, so the ion collision can not only remove the etched film, but synchronously remove the photoresist).

The conventional fabrication method of the micro-electro-mechanical structures must need fabricating a layer of precision mask for restricting the etching, but the mask technology is different from the technology of the deposition of the insulation layer.

Therefore, the recent micro-electro-mechanical structure manufacturers mostly apply another process (or different manufacturer) to fabricate the masks, so that the mask becomes more and more elaborate, thus increasing the manufacturing cost and limiting the dimension and precision of the microstructures.

2. In the process of this conventional technology, the micro-electro-mechanical structure is exposed in the process at first, after a long time of multi-layer processing, the exposed micro-electro-mechanical structure is likely to be contaminated and damaged, causing an excessively low yield rate;

3. The exposure of the metal layer during the process of etching is likely to cause contamination of the chamber of the etching machine by metal and cause unstable etching rate.

This technology is capable of greatly reducing occurrence of undercut, but since it also conducts a layer-by-layer etching from up down, and the last etching operation of the silicon substrate must apply the transverse etching technology, this improved conventional technology is still complicated and has the undercut problem.

It is important that, some problems still have not been improved, such as: the exposure of the micro-electro-mechanical structure and affecting yield rate, etc.

The problem that cannot be solved by the existing technologies is that, a layer of precision mask is still needed for precisely finishing the etching operation, but the micro-electro-mechanical structure has become more and more elaborate, so the fabrication of the mask becomes more and more difficult, thus not only increasing the manufacturing cost, but also causing troubles in transmission, error, cost and particle contamination.

In addition, the shorter the distance between the mask patterns is, the smaller the etching hole will be.

The reactant and the ion with energy in the etching system cannot reach and contact the predetermined bottom, or the reaction products cannot be fully discharged out of the hole, thus leading to the reduction of the etching rate.

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